JP2007199529A - Reflection-type projection screen and reflection-type projection display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection-type projection screen of such a type that the Fresnel lens surface is used as a reflecting surface, wherein the influence of shadow due to an obstacle is eliminated, and successful image display is realized, without causing contrast deterioration under bright environmental light, and to provide a projection system (display device) that uses the reflective projection screen. <P>SOLUTION: The reflection-type projection screen 102 is provided with a light transmission diffusion layer, on the surface side of a transparent sheet and a circular fresnel lens surface for light reflection on the back-surface side, wherein the circular fresnel lens surface has an offset structure such that the optical center is shifted to the upper side or the lower side than the geometrical center of the screen, and has such abaxial reflection characteristics so as to reflect the projection light from a projector 101, having a projection lens in a direction substantially parallel to incident angle 70 to 80°, with respect to the screen surface as substantially parallel light around the vertical direction to the screen surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projection screen (reflective screen) for observing image light that is arranged on the projection side and reflected (imaged) with respect to various projection apparatuses.

  Equipment such as OHP (overhead projector) and projectors using 16mm and 8mm film are used in conferences and projection meetings, etc., and in recent years, home theaters have become smaller due to downsizing of projectors and lower prices. The demand for home use such as the above has increased, and projection systems are increasingly used in ordinary homes.

In this case, the projection system is often installed in a living space at home, but such a place is usually designed to easily receive ambient light such as outside light and illumination light.
For this reason, a projection screen used in a projection system for home use is desired to be able to realize a good video display even under bright ambient light.

There are various types of screens arranged on the projection side with respect to these devices, and they are selected and used according to the application.
Of these, even if the screen is a flat plate that does not bend in a parabolic shape, even if the decrease in peripheral luminance is small and the direction of the projection light from the projection device is limited, there is no need to tilt the screen. In order to control the directivity of image light that is reflected and viewed as a type screen, a proposal related to a reflection type screen having a Fresnel lens surface as a reflection surface is known. (For example, see Patent Documents 1 to 3)

Japanese Patent Laid-Open No. 5-232581 JP-A-10-62780 JP 2005-134448 A

Patent Document 1
A reflective screen comprising a light transmissive layer laminated on a linear Fresnel surface having light reflecting and condensing properties in one direction. (Claim 1)
It is.

Patent Document 2
A light transmissive base,
In a reflective screen that is formed on the back side of the base part and includes a reflective part having a reflective surface,
A Fresnel lens shape is formed on the base part or the reflection part,
The reflection type screen characterized in that the optical center of the Fresnel lens shape is shifted downward from the geometric center of the screen. (Claim 1)
It is.

Patent Document 3
A reflective screen for projecting an image projected from a projection device, the reflection screen having a reflection surface for reflecting the projection light from the projection device, wherein the reflection surface is made constant by making the projection light from the projection device parallel to each other A reflective screen, characterized in that it is formed to reflect in the direction of. (Claim 1)
It is.

  When using the projector body (projector) and a reflective screen in combination, if the projector is projected away from the screen surface, an image enlarged on a large screen can be obtained, but the space between the projection lens and the screen surface is wide, If a person crosses the space or there are obstacles, the shadows appear on the screen. The closer the obstacle is to the projection lens of the projector, the larger the shadows appear, and the projected image is damaged. In many cases, however, there have been no reports on reflective projection screens that have been reported to eliminate the effects of shadows due to obstacles.

  The present invention eliminates the influence of shadows due to obstacles in a reflective screen of the type having a Fresnel lens surface as a reflection surface, and can realize a good image display without causing a decrease in contrast under bright ambient light. An object of the present invention is to provide such a screen and a projection system (display device).

The reflective projection screen according to the present invention comprises:
A light transmissive diffusion layer is provided on the front side of the transparent sheet, and a circular / Fresnel lens surface for light reflection is provided on the back side.
The circular Fresnel lens shape is an offset structure whose optical center is shifted above or below the geometric center of the screen,
Off-axis reflection that reflects projection light as projection light from a projector having a projection lens in an approximately parallel direction with an incident angle of 70 to 80 ° with respect to the screen surface as approximately parallel light centering on a direction perpendicular to the screen surface. It has the characteristics.

  The light reflecting layer formed on the surface of the circular Fresnel lens is preferably made of a gray or black material, and a nichrome film is suitable.

  The light transmissive diffusion layer may have a colored light transmissive property obtained by dispersing and mixing black colored particles in addition to the light diffusing particles in the binder.

A space-saving projection system (reflective projection display) configured by combining the above screen and projector.
A screen having a reflective surface that emits divergent light projected from a substantially parallel angle with an incident angle of 70 to 80 ° with respect to the screen surface, and exits the optical axis in a direction substantially perpendicular to the screen surface;
A projector that illuminates the screen with the light of the angle;
The screen is arranged along a wall surface in the room.

  Projection light is efficiently reflected as projection light from a projector having a projection lens in an approximately parallel direction with an incident angle of 70 to 80 ° with respect to the screen surface as substantially parallel light centering on a direction perpendicular to the screen surface. Therefore, the display device (reflective projection display) has a thin and compact configuration (within 400 mm) in the depth direction from the screen surface to the projector, and the problem that the shadow of the obstacle is reflected on the screen surface is solved. When observing the projected image in a bright room, the reflection phenomenon that the observer's face and the background behind the viewer can be seen together with the projected image is obstructed. .

Because it has a light transmission diffusion layer on the surface side (observer side), it not only eliminates glare on the screen surface due to ambient light (stray light such as illumination light) but also reflects light from the screen (video display) The light emission range (up / down / left / right) can be controlled by the Fresnel lens shape and the light transmission diffusion layer.
Furthermore, by using a coloring material on the reflecting surface, a projected image that does not decrease contrast even in a bright room environment can be viewed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective explanatory view schematically showing a reflective projection display 100.
The reflective projection screen 102 is observed by reflecting the image light 103 from the projector 101 by a reflecting surface having a circular Fresnel lens shape in which the optical center is shifted downward from the geometric center of the screen. The

The projector 101 and the reflective projection screen 102 have a structure that is fixed and integrated on a support base 104, and the screen 102 is arranged and used along a wall surface in the room.
In the integration, it is necessary to maintain the conditions of the projection angle (70 to 80 °) and the projection distance from the projector 101 to the screen surface so that ideal image light can be seen.

  When the projection angle is an angle substantially parallel to the surface of the screen 102 (70 to 80 °), the distance from the wall surface of the room to the projector 101 is shortened in the depth direction. The influence of the shadow due to the intervention is eliminated.

  In addition, the projector 101 and the reflective projection screen 102 can be separated without being integrated, and can be used in combination when viewing images. The relative positional relationship between the projector 101 and the reflective projection screen 102 can be determined by the user. Must be adjusted (mainly by appropriately changing the installation of the projector).

FIG. 2 is a cross-sectional explanatory view of a reflective projection screen used in the present invention.
This is because the surface corresponding to the outermost surface on the observer side has an irregular fine uneven shape 201 and functions so as to suppress glare caused by light projected from the projector (AG; anti-glare).
It is desirable that the outermost surface further has an antistatic function (AS) or an abrasion resistance function.

A display with a wide viewing angle is desirable, and in this embodiment, the light transmission diffusion layer 202 is provided to increase the viewing angle.
The light transmissive diffusion layer is usually provided with a filler having a different refractive index in the base substrate to give the effect, but depending on the filler used, the diffusion layer is yellowish. May end up.
In particular, when the color temperature is lower than 4500K, the color becomes yellowish that can be visually recognized by an observer, which causes a decrease in color reproducibility.
In the present embodiment, by mixing at least one kind of inorganic filler in the diffusion layer to be used, a decrease in color temperature can be suppressed, and arbitrary color reproducibility can be realized.

The translucent base material 203 and the circular Fresnel lens 204 as the base are selected from acrylic resin, styrene resin, acrylic-styrene resin, polyester resin, polycarbonate resin, etc., using a mold having a predetermined lens shape, for example. The translucent resin to be formed can be molded by techniques such as press molding, cast molding, and injection molding.
In this case, the translucent base material and the circular Fresnel lens are made of the same material in an integrated form.
Furthermore, a cheaper product can be obtained by using an ultraviolet curable resin for the translucent substrate and molding using the mold.

  The light reflecting layer is preferably one that reflects the projection light but has a black color to improve contrast, and further, one that does not change its color over time, that is, one that is difficult to oxidize. Nichrome which is an alloy of is effective.

<Reflective projection screen>
A light transmissive diffusion layer was formed by dispersing an acrylic / styrene filler as an organic filler and a talc filler as an inorganic filler on an acrylic / styrene base substrate.
By depositing the filler in the light transmission diffusion layer on the surface, a matte feeling was given and a function as an AG layer was imparted, and the filler was disposed on the outermost surface of the screen.

Molding was performed on an acrylic / styrene base substrate using an ultraviolet curable resin to obtain a predetermined lens shape.
The lens shape (design) is designed so that the projection distance from the projector to the screen is about 380 mm, and the lens at the focal length is close to 70-80 ° parallel to the lens surface. In order to correspond to the portion where the focal position comes, a Fresnel lens is formed by removing the geometric center of the concentric unit lens group downward.
The offset structure in which the optical center of the circular Fresnel lens shape is removed above the geometric center of the screen is effective when the projector is used while being fixed on the top rather than the floor.
Finally, a nichrome thin film was formed on the surface of the Fresnel lens by vapor deposition or sputtering to obtain a reflective projection screen (40-inch size) having a gray or black reflective surface.

The screen according to the present embodiment has little glare from outside light and projection light from the front, and is thin in the depth direction as a projection display, thereby reducing the possibility of viewing unnecessary shadows.
The color temperature was about 6000 K, and an effect of suppressing yellowishness by selecting a filler was obtained.
The contrast in a 200 lux environment was also about 200, and by controlling the hue of the reflecting surface (Nichrome), a sufficient effect without a decrease in contrast was obtained even by visual observation in a bright room.

FIG. 6 is a perspective explanatory view schematically showing the reflective projection display 100. Cross-sectional explanatory drawing of the reflective projection screen 102.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reflective projection display 101 Projector 102 Reflective projection screen 103 Image light 104 Support stand 201 Fine uneven | corrugated shape 203 Translucent base material 204 Circular Fresnel lens

Claims (6)

A light transmissive diffusion layer is provided on the front side of the transparent sheet, and a circular / Fresnel lens surface for light reflection is provided on the back side.
The circular Fresnel lens shape is an offset structure whose optical center is shifted above or below the geometric center of the screen,
Off-axis reflection that reflects projection light as projection light from a projector having a projection lens in an approximately parallel direction with an incident angle of 70 to 80 ° with respect to the screen surface as approximately parallel light centering on a direction perpendicular to the screen surface. A reflective projection screen characterized by having characteristics.   2. The reflection type projection screen according to claim 1, wherein the light reflection layer formed on the surface of the circular Fresnel lens is made of a gray or black material.   3. The reflection type projection screen according to claim 2, wherein the light reflection layer is made of a nichrome material coating.   The light transmissive diffusion layer is configured by dispersing and mixing light diffusing particles having a refractive index different from that in a binder, and the light diffusing particles include at least an inorganic filler. 4. The reflection type projection screen according to any one of 3 above.   5. The reflection type projection screen according to claim 4, wherein the light transmission diffusion layer is colored and translucent formed by dispersing and mixing black colored particles in addition to the light diffusing particles. A screen having a reflective surface that emits divergent light projected from a substantially parallel angle with an incident angle of 70 to 80 ° with respect to the screen surface, and exits the optical axis in a direction substantially perpendicular to the screen surface;
A projector that illuminates the screen with the light of the angle;
And a support base, and the screen is disposed along the wall surface of the room.